


Upgrade

by Crims0nKitty



Category: Dr. STONE (Anime), Dr. STONE (Manga)
Genre: 69 (Sex Position), Anal Sex, Aphrodisiacs, Blow Jobs, Creampie, Daddy Issues, Daddy Kink, Dirty Talk, Fluff and Smut, Food Kink, Hand Jobs, M/M, Multiple Orgasms, Parent/Child Incest, Plot What Plot/Porn Without Plot, Rimming, Shotacon
Language: English
Status: Completed
Published: 2021-03-15
Updated: 2021-03-15
Packaged: 2021-03-23 17:49:02
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 3,806
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/30059262
Author URL: https://archiveofourown.org/users/Crims0nKitty/pseuds/Crims0nKitty
Summary: Gen was only seven years old, but his intellect had already surpassed any outstanding high-schooler. Never in his life did Kuro think he would become a doting father. But he did. With a small addition of not only being Gen's parent but also being his… lover.
Relationships: Asagiri Gen/Ishigami Senkuu, KuroSenku/Asagiri Gen
Comments: 6
Kudos: 22





	Upgrade

**Author's Note:**

  * For [drabbles4gennie](https://archiveofourown.org/users/drabbles4gennie/gifts).



> A pwesent for the love of my life @drabbles4gennie  
> HAPPY BIRTHDAY BB I LOVE YOU SM HOPE U ENJOOOY
> 
> -Ogy♡

"Daddy, did you call?"

Kuro turned around in his chair, looking at the doorway where his creation stood. With a smirk he beckoned the boy closer, "Yeah, come on in, sweetie."

Crimson eyes intently watched the little creature that was approaching him. "Good boy, hop on," Kuro softly murmured, patting his lap as soon as his creation stood quietly in between his spread legs. He was  _ so  _ small, barely reached Kuro’s bellybutton with his nose when he stood.

"M...mhm," Grabbing the lapels of his daddy’s lab coat with his tiny hands, the boy climbed in the brunette’s lap, letting out a huff.

"How are you doing, Gennie~?" Kuro’s voice was but a purr, as he wrapped his large hand around Gen's waist, bringing him even closer, "Did you study today?"

Kuro always made sure to be a good father to his creation. After all, Gen was a part of him... and some other unfortunate human being that he was lucky to catch in his claws. Although, his boy would never find out what he really is. An inhumane experiment. A child from a test tube. His whole appearance was carefully created and orchestrated by Kuro.  _ "The paragon of human creation," _ That’s how his father called him.

Gen was only seven years old, but his intellect had already surpassed any outstanding high-schooler. Never in his life did Kuro think he would become a doting father. But he did. With a small addition of not only being Gen's parent but also being his…  _ lover _ .

"Mhm! I studied existential-humanistic theories!" The boy squirmed, bravely looking in his dad’s eyes, searching for any kind of praise or approval.

Kuro hummed, ruffling Gen's bicoloured hair, "And what about your physics homework?"

"I—W...Well…I tried my best, Daddy…But I'm still not sure whether I'm right or wrong… Physics is haaaard…" He softly nuzzled his face into Kuro’s chest, trying to be as cute as possible, hoping for mercy.

With a low chuckle, Kuro lifted the boy's face up, pressing a soft kiss on his forehead. "It's okay, darling, we'll look through it together later. Magnetohydrodynamics isn't something that you can understand from the first try." The brunette stood up, holding his boy under his butt, "You've been such a good boy for me lately, how about I give you a little reward? I've made it just for you~"

Gen's grayish eyes immediately lit up with excitement. The boy wiggled in Kuro’s grip a bit, wrapping his little hands around the man's neck, "Yes! Please, please— I want it!!"

Not saying anything else, the brunette kissed Gen's chubby cheek and started strolling to his room, enjoying the way his son's small body pressed against his chest.

Upon arriving, the man set his boy on the bed, silently going to one of his drawers, looking for the promised reward.

Gen was so excited, basically shaking from anticipation. Daddy made something for him. Just for him! Daddy loved him… Gen's cheeks tinted red just a bit at the thought of this reward. Kuro usually was pretty passionate and loving, he made sure his son got the best kind of pleasure every time they did something… something that Gen was embarrassed to think about, yet his mind always swayed back to Kuro’s strong hands on his--

"Here."

"Oh—Cola...?" The boy took the cold bottle in his hands, trying his best to hide a bit of disappointment in his voice. Of course Gen liked Cola, it was his favorite drink...but to his own embarrassment that wasn't exactly what he had in mind.

"Mhm~ Do you not like it?" Kuro asked with a sly grin on his face. He knew what was going on in his mind: after all, he was Gen's father.

"N...No...I—"

"Don't worry, it's not  _ just _ Cola~ I made it myself, with a bit of a special ingredient~" 

_ Aphrodisiac _ . He added aphrodisiac. Quite a lot of it too.

Gen wasn't just a regular boy. Not even close; as a part of his parenting Kuro ran tests on his son. Obviously, almost none of them were painful or harmful to his boy. It was only logical to do this, after all: Gen was a superior human form. If Kuro was to compare him to some equal creature known to man, he would say that Gen was a vampire. The boy even had little fangs! How cute was that?

To Kuro’s luck, the boy had the perfect qualities for a test subject: incredibly fast regeneration, increased vision (during the night as well), considerable strength and stamina. To be honest, the scientist had his doubts about Gen's immortality. This matter was still open for tests and discussions.

For now, Kuro was content to experiment with Gen's stamina, his reproductive abilities to be exact. Being one of a kind, the boy had to have powerful instincts; he had to  _ breed _ to survive, to pass on his genes. One day Kuro would give him that chance. Maybe he would create more of those like Gen. His own dynasty… Artificial evolution of mankind. What a thrilling thought... To be the one to push humans to ascend the next step. That's  _ God's _ work.

A few crazy giggles slipped from Kuro’s smirking lips as he cracked open the bottle, pressing it against Gen's willing mouth. 

"C'mon, GenGen~ Daddy made this just for you~"

With a sigh, the boy obediently parted his lips, looking up at his father. This scene was awfully familiar for the both of them, with the exception of the bottle.

"Mnh... Mmm…" Gen licked the cold glass, encouraging Kuro to tilt the bottle and finally give him his reward. As soon as the cold liquid started running down the boy’s throat, he whined at the taste and the amount. Gen was almost choking on the sugary fluid; it was definitely more sweet than the regular one. Not that he minded, not when his daddy looked down at him with such adoration and obsession. 

“Mhhhmmm~ Yeah~ Just like that, sweetheart, take it aaaaall in~” The scientist was ecstatic over his obedient boy. The way he desperately gulped down everything that Kuro gave him, instantly made the brunette’s pants just a bit tighter.    
  
“Haa-aah…” After emptying the bottle, Gen let out a harsh gasp, falling back onto the bed while trying to steady his breathing. “D...Daddy...Is it supposed to feel...mhh--” The boy involuntarily bucked his hips into the air. In his mind clouded by lust, Gen still hadn’t realized how painfully erect he was in his shorts. 

_ “Wow.” _ Kuro thought in his head,  _ “Just how quick is his metabolism? It’s only been two minutes since he’s made the first gulp… Absolutely fascinating…”  _ Taking a deep breath, the scientist sat beside the boy, gently undoing his shorts and pulling them down along with his underwear.  **God** , did Gen look good right now - all squirming and whining, his small chest heaving from arousal, tiny hands slowly sneaking to his cute leaking cock. There was so much precum, too much for a seven-year-old for sure.

"Shhh, I've got you, love." Moving Gen's palms away, Kuro moved to rest his back on the wall, as he tugged the boy in his lap, softly purring in his ear, "Do your best for daddy, show me how much you like your reward~"   
  


“Yes! Yes, yes, yes— A..aahh..a..anything for you…”

Gen was desperately bucking his hips into the air, his tiny hands gripping Kuro’s in attempts to steady himself. It was quite cute to see his boy in such a state: all hot and bothered, his small cock twitching at every little touch, rosy lips parted, letting out all kinds of needy sounds. With a grin, the brunette pressed two fingers against Gen's mouth, pushing them in. A shiver ran down Kuro’s back as his boy immediately started sucking on them. "Mhh~ You know what to do, don't you, Gennie~?" A sly coo slithered out of the man's throat. He was so proud of his son, his baby boy was so clever and loyal, not even once did he disobey his daddy’s orders.

Getting too impatient for foreplay, Kuro finally wrapped his hand around Gen's small cock, earning a myriad of loud whines from the boy, as he started stimulating his sensitive tip with his thumb.

"Da—AHH-!! D...daddy...mm… I want…Nhhhh p...please!!" Gen clearly had a hard time talking, so lost in pleasure and desire already. 

"Mhm, tell me what you need. Daddy will give it to you." With every minute Kuro’s breath got more and more heavy, laced with need for more. His cock throbbed in his pants every time his little boy pushed into his hand or called out for him. He needed to be inside him. The brunette was sure that Gen could feel his hardness rub against his ass, this fact made Kuro wonder what was on his son's mind right now.

His question was answered not too long after, when the boy let out a pitiful whine and turned on his stomach with a cute desperate huff. Gen looked up into his father’s eyes with a pleading expression on his face, never stopping the movements of his hips, "Please… mm… please daddy… can you… a-aaah.. can you b-be inside me? I c-can't finish without it… I've tried and I can't…"

**_Oh fuck._ **

Kuro couldn't hold back a throaty groan when he heard his boy's words.  _ He can't cum without my cock. He tried to touch himself. Fuckfuckfuck-- _

"Oh~? Looks like my little Gennie is a naughty boy, huh~? Such a slut for your dad, aren't you~?"

"N-No-!" Gen's entire face flushed as he heard Kuro degrade him. Usually the boy didn't like being called names and being made fun of, but… There was something special about his dad calling him a slut… He didn't understand why, but it made him incredibly needy…

"Don't deny it, love, just ask for it~" Kuro squeezed his cute butt in his hands, barely holding himself back.

The boy frowned, crawling up to his dad’s face. Even though he was almost on the verge of crying out of desperation, he wanted to be good for daddy.

"Mnh… Daddy can you… put your… c-cock inside me…?" Gen was burning up from the embarrassment, but the words that his father taught him to use slipped from his lips effortlessly. The tension was unbearable for him, so the boy squeezed his eyes shut and pressed his lips against Kuro’s in an innocent kiss.

Those words accompanied with such a sweet kiss was all it took for the brunette to break. With a possessive grunt, Kuro tugged Gen closer, licking into his mouth, making the boy whimper from the feeling of their tongues intertwining and sliding along each other.

"Good… mnh… good boy." 

Pulling away, the older male looked his son over, loving the frantic movements of his hips.

Sadly, Kuro couldn't just make Gen sit on his dick. Even though his boy had an excellent regeneration and pain endurance, there was no need to hurt him. With a loving look in his eyes, Kuro gripped Gen's hips and lifted him over his face, spreading his asscheeks with his thumb and looking at the boy's cute hole. The father could already feel his mouth water from such a sight. With no hesitation, Kuro lowered Gen's ass on his face, hungrily lapping at his entrance, occasionally pushing his tongue inside.

"AH!! MHH-!! DADDY-!" Gen was instantly sobbing from the pleasure and embarrassment, a few tears falling from his eyes as his dad pushed his tongue against his sweet spot.

The boy’s little hands found their way into Kuro’s black locks, tugging and holding on them for dear life as Gen writhed on top of his dad. His little cock rubbed against the older man’s face, which made him slightly embarrassed, but for Kuro this feeling was pure bliss. His son’s cute dick left stains of precum on his cheeks and forehead. This feeling was making Kuro grip his boy’s ass a bit harder.   
  
“Ghaah— D-Daddy… h..hurts--”   
  
“Mhh… S-Sorry, sweetheart— got carried away.” Kuro softly kissed the inside of Gen’s thigh before setting him on the bed, deeming that his baby had enough of prep. For the brunette’s size, there was no amount of stretching that would prevent all the pain. Kuro was just thankful that Gen was willing to put up with aching muscles for him.

The man turned away from Gen and started undressing just a bit too slow for his boy’s liking. Kuro was just waiting for the other to start begging.    
  
“Nooo… Daddy, I wanna watch…”

Letting out a huff, Kuro faced his boy, his hands slowly sliding to the bottom of his black t-shirt and lifting it just a little bit to get those curious grayish eyes where he wanted, "Why do you want to watch your father get undressed~?"

All these questions and adult words felt surreal to Gen, he knew many things and had a quick-witted mind, but… he was still a child. So when Kuro asked him something like that, he felt so confused. Was he not supposed to like how his dad looked? Was he not supposed to desire his father? To be honest, the nature of the word desire was obscure to him as well. Gen didn't understand those feelings.

Nevertheless, when he watched Kuro unhurriedly shrug his lab coat off his broad shoulders and tug his t-shirt off in a tantalizingly slow manner, the boy couldn't suppress the little buck of his hips. The way the dim lights played on his dad’s porcelain skin made Gen whimper with need.

"Should I continue~? Tell me what you want, darling~" Kuro ran his large hands along his chest, moving them to his hip bones. "I'll be obedient for you~"

The way his father spoke to him always made Gen blush and squirm, but this was something new. Kuro… obedient just for him… What should he even say… 

"Mmm… t-take off your… p...pants… Daddy..."

"As you wish~"

The older male got to work, leisurely undoing the belt and the button. The sounds of the zipper sliding down and Kuro’s pants dropping to the floor were way too loud in the silence of their bedroom; Gen could feel some sort of tension between them, could feel the way his dad's eyes burned into his soft skin and ogled his cute twitching cock.

When Kuro’s thumbs hooked into the waistband of his boxers, Gen held back his breath, gulping at the thought of finally seeing him nude.

"Oh~? Does my baby want to see something special~? Or do you wanna take it yourself~?"

Usually the boy wasn’t so eager to make first moves or have an active role in bed, but right now when he felt copious amounts of aphrodisiac flowing through his veins, he couldn’t resist his inner urges. Shyness and embarrassment were pushed back as he kneeled on the bed in front of Kuro, replacing the man's hands with his own. Ripping his dad’s boxers off, he almost got slapped in the face as Kuro’s cock sprang free.

The brunette cackled, ruffling Gen's bicoloured hair in a reassuring gesture, "Pftt~ Be careful, sweetheart~"

Gen would answer if he wasn't so enamored with his dad's thick manhood. The boy quickly closed his eyes and bent down to lick a long wet stripe from the base to the tip, feeling it violently twitch against his lips as he took the tip in his mouth. Kuro taught him a lot of stuff: physics, chemistry, biology and… how to bring him pleasure. The last one was Gen’s favourite subject.

“Eager today, aren’t you~?”   
  
“M...Mhh…”   
  
Not opening his eyes, Gen parted his lips and slid half of Kuro’s length down his throat. He physically couldn’t take more, no matter how hard he tried. However, for the brunette that was enough to let out a shaky groan and buck his hips forward just a bit. To be honest, he was on the edge. Kuro really needed to be inside his boy.

Gen steadily worked his mouth around his dad’s cock, occasionally whimpering and rubbing himself against the mattress. It was a wonder how the boy still had himself under control, considering the amount of aphrodisiac that was currently clouding his mind and making his skin tingle.   
  
“Goood, you’re incredible baby--”

Gently tugging on Gen's hair, Kuro made the boy look up at him. His baby always had the most beautiful eyes - gray mixed with blue, always opened wide and staring at him with the utmost devotion. "On your hands and knees, dear." Pulling out of Gen's hot mouth, Kuro wiped the excessive drool off the boy's chin. Staying calm was becoming more and more difficult with every second spent not being inside Gen.

His son gave him a smile before enthusiastically crawling to the pillows and hugging one while perking up his butt for daddy.

After getting the lube, Kuro also got on the bed, sitting behind Gen, his eyes hungrily ogling his boy’s twitching hole. There was no time to wait, the brunette’s cock throbbed too hard to play around any longer. Pouring generous amounts of lube onto Gen’s awaiting entrance, Kuro rubbed it with his thumb, gently pushing some of the gooey liquid inside the boy, making him twitch and shudder. “Shh, don’t worry, sweetheart, I’m gonna be inside you soon.” Kuro crooned, lathering his cock up and pushing the length between his boy’s asscheeks.

God, Gen was so fucking small. Sometimes Kuro questioned just  _ how _ his son took him.

“Ready?”

“Mmm… Yes! Daddy, please! I can’t wait anymore-!”

Satisfied with the answer, the brunette pushed the tip in, already hissing from the tightness. Gen was writhing underneath him, trying to get more of his length inside his ass. The boy was really cute but his movements were making it hard for Kuro to enter him with no pain, so the man laid his hand on Gen’s back, pinning him to the bed while sliding the rest of his shaft in with a loud groan.

“GHAH—! D-DADDY!! SO DEEP—!” Gen sobbed, trembling from the sudden pain and pleasure. He could feel his tummy being stretched by Kuro’s cock. It seemed almost too much, but his dad was always pushing him to his limits. Affected by the aphrodisiac, Gen couldn’t care less about pain. The boy could only lie there underneath the bigger man and whine while tears of pleasure streamed down his face.

“God, Gennie, you’re so f— so tight—”

Kuro couldn’t wait anymore. He started a slow pace, pulling out till only the tip was in and then pushing back inside. Every little movement made his son let out a wail.

“D...addy… I’m—gh-!!”

With a sense of pride and surprise, Kuro watched Gen cum in his arms. Seemed like his boy truly needed his cock to reach his peak. The man slowly pet his back, not stopping his thrusts, which made Gen squeal and whine.

“Wow, so lewd~ We haven’t even started, and you already came~ Want me to stop~?”

“N-NO—!” The boy clenched down on Kuro’s cock even harder, shakily trying to move his hips at the same pace as his dad, “Please, please, don’t stop—! I need more-! I wanna do it again, daddy-!”

Curiously, Kuro snaked his hand between Gen’s thighs and surely enough found out that his cute tiny cock was hard and ready again. This fact made his own member twitch from arousal.

Taking a deep breath, Kuro moved his hands back to Gen’s hips, sliding his thumbs against his milky peach soft skin. Leaning down, he licked a wet stripe across his son’s neck, biting into it shortly after.

“Get ready.”

That was the only warning Gen got before his mind was wiped clean with the feeling of overwhelming pleasure. Kuro started going as fast as he could, his hips slapped against the boy’s ass making a lot of lewd noises, but neither of them cared about it. Gen was moaning too loud to hear anything beside his pitiful cries.

“NGHHH—! MHHHAAHH!! D-DADDY—!! SO-SO MUUUUCH—!”

Kuro was merciless right now, slamming his cock inside the boy’s needy hole so hard that if Gen was human, he would surely break. But his son could take it, could take anything that Kuro gave him.

“Oh my gooood, Gen— Gh… Daddy’s gonna cum s...soon… you’re too good—”

Kuro rasped into his ear, his movements becoming a bit uneven and twitchy. In his fast and wild pace, he didn’t even realise just how close he was to his own peak. Gen was too tight, too responsive; nothing made Kuro lose his mind like his son did.

Barely hearing what the man above him said, Gen happily whined, perking his butt up even more for Kuro.

“Mhhh- mhm! P-Please, daddy, fill me up-! I need it!!”

This was the last straw for the older male. With a growl, Kuro grabbed Gen’s ass even tighter, making a few harsh thrusts before spilling inside his son’s ass, letting out a raspy groan.

“G-Gen-! So...So good for me— taking my cum so well~ ahhh— my little cum slut~” The man couldn’t keep in a few degrading words as he lovingly kissed Gen’s neck, calming down from his high. This was incredible. Every time he has sex with his son, it leaves him breathless and spent.

Pulling away, Kuro let out a pleased hum as he looked down at the sinful view. Gen was lying underneath him, whining and sobbing in complete bliss; it seemed like he came again from the feeling of his father’s load inside him. Kuro’s cock was still buried in his ass, although his cum was still dripping out of Gen’s hole - there was just too much of it.

With a lewd squelch, Kuro pulled out, lying down next to the boy on his back.

He wearily moved his hand to pet Gen’s head, “You did so good for me, sweetheart… so good…”

Getting something incoherent in return, Kuro chuckled, closing his eyes. His boy needed more training. No matter how many stimulants he gave him, Gen was still just a child with a limited amount of stamina. Although, to be honest, Kuro was spent as well.

After a few minutes, the man was ready to fall asleep when he felt tiny hands on his lower stomach followed by the weight of his son crawling on top of him.

“Wha-”

“Mmm… Daddy… I need… M-More…” Gen whined, looking deeply into Kuro’s eyes. Apparently the aphrodisiac in his blood was still working, and working pretty goddamn well.

With a groan, Kuro tugged his boy into a kiss, getting an eager response. It looked like the man would have the most intense night in his life.


End file.
